1. Field of the Invention
The present invention relates to an assembling apparatus using back-up pins for supporting a printed circuit board. More specifically, the present invention relates to an assembling apparatus in which electronic parts are mounted on a printed circuit board supported by back-up pins which are detachably disposed at predetermined positions in accordance with the type of the printed circuit board on a mounting table.
2. Description of the Prior Arts
In an apparatus for subjecting a printed circuit board to working such as mounting of electronic parts and application of adhesives, a printed circuit board back-up device for supporting the printed circuit board without causing flexing is required. A printed circuit board having no parts mounted or adhered on its reverse surface may be deposited on a plate-shaped supporting member but a printed circuit board having parts already mounted on its reverse surface may not. Therefore, there is a printed circuit board back-up device so constructed that a base plate is provided with a plurality of throughholes, back-up pins are detachably inserted in the throughholes, and a lot of points on the reverse surface of a printed circuit board are supported on the back-up pins. One example of the apparatus having such construction can be seen in Japanese Patent Laid-Open Gazette No. 59-29492 Feb. 16, 1984).
The above described printed circuit board back-up device is so adapted that a worker replaces back-up pins with the change in the type of a printed circuit board. The worker, therefore, must perform a work while confirming the position of each back-up pin. Accordingly, when the type of the printed circuit board is changed, the preparation takes a lot of time and labor. In addition, an error in position of the back-up pin often occurs.
In addition, an apparatus capable of solving such a problem of the conventional apparatus is disclosed in, for example, Japanese Patent Laid-open No. 1-117099 (May 9, 1989). In this prior art, when a printed circuit board to be processed is changed, the back-up pins are automatically changed by a back-up pin mounting device. More specifically, when the printed circuit board is changed, a printed circuit board positioning table on which no back-up pins are mounted is moved to the back-up pin mounting device, and the back-up pin mounting device removes unnecessary back-up pins of the back-up pins which were mounted on the positioning table for a printed circuit board which has been assembled and mounts necessary back-up pins on the positioning table for a printed circuit board to be assembled next.
However, the prior art disclosed in Japanese Patent Laid-open No. 1-117099 has a further following problems to be solved. More specifically, since the printed circuit board positioning table is moved to the back-up pin mounting device when the back-up pins are to be replaced, moving power systems for moving the positioning table requires an X direction driving system and a Y direction driving system because the back-up pin mounting device is fixed at a predetermined position. In addition, in order to select electronic parts arranged in a predetermined direction, a mount head having a suction chuck is to be moved in the predetermined direction. Therefore, in the prior art disclosed in Japanese Patent Laid-open No. 1-117099, it is necessary to provide three driving systems, and therefore, the construction becomes complex and large, and the cost becomes high.